This application relates to the art of heaters and, more particularly, to heaters of the type used for heating devices that are illuminated by a light source. The invention is particularly applicable to heaters used with liquid crystal displays and will be described with specific reference thereto. However, it will be appreciated that the invention has broader aspects and can be used for providing heat to other devices.
A known type of heater includes one or more electrical resistance heating elements mounted to a support member that is pervious to light. Heaters of this type require separate temperature responsive controls for turning the heater on and off.
Another type of heater includes positive temperature coefficient thermistors mounted to an opaque support. This type of heater requires no separate temperature responsive control because the thermistors are self-limiting. However, a special source of illumination is required because the support for the thermistors is opaque.
It would be desirable to have a heater that required no separate temperature responsive control or any special type of illumination for devices associated with the heater.